NMR Probe Dual-Shield Design for Magnetic Field Control
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Solution Overview
Problem
Existing NMR probes face challenges in suppressing high-frequency magnetic field irradiation to regions outside the observation object, leading to reduced resolution and increased high-frequency loss due to the diffraction of magnetic fields and heat-induced resistance increases in shields.
Innovation Solution
The NMR probe incorporates a dual-shield configuration, where a room-temperature shield is placed on the outer surface of the sample temperature control pipe and a low-temperature shield between the detection coil and the room-temperature shield, with strategically sized window sections to block high-frequency magnetic fields, reducing irradiation to unintended areas and maintaining the Q value of the detection coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shield is provided to block high-frequency magnetic field irradiation to regions outside the observation object, then the resolution of NMR spectrum is improved, but the shield absorbs high-frequency magnetic field energy causing increased high-frequency loss and decreased Q value of the detection coil
Solution Approach 1:
The shield is divided into multiple segments with different properties: a room-temperature shield and a low-temperature shield. The room-temperature shield blocks magnetic field diffusion to improve resolution, while the low-temperature shield specifically protects against high-frequency magnetic field absorption, thereby reducing energy loss and maintaining Q value.
Solution Approach 2:
Different regions of the shield structure are assigned different temperatures and functional properties. The room-temperature shield is positioned to handle magnetic field diffusion blocking, while the low-temperature shield is positioned to minimize high-frequency energy absorption. This local differentiation of properties allows simultaneous achievement of high resolution and low energy loss.
2Loss of energy
If the shield is placed closer to the detection coil to reduce high-frequency loss, then the Q value is maintained, but the shield blocks the magnetic field necessary for observation of the sample
Solution Approach 1:
The shielding function is segmented between two distinct shields: the low-temperature shield positioned near the detection coil to maintain Q value, and the room-temperature shield positioned to control magnetic field diffusion for resolution. This segmentation allows each shield to be optimally positioned for its specific function without compromising the other.
Solution Approach 2:
The room-temperature shield acts as an intermediary between the low-temperature shield and the sample region. It manages the magnetic field diffusion that would otherwise reach the sample, while allowing the low-temperature shield to maintain its position near the detection coil for Q value optimization.
3Device complexity
If a single shield is used to block both magnetic field diffusion and high-frequency irradiation, then the structure is simple, but it cannot simultaneously achieve high resolution and low high-frequency loss
Solution Approach 1:
Rather than using a single complex shield, the system employs two simpler shields with distinct functions. The room-temperature shield handles magnetic field diffusion blocking, and the low-temperature shield handles high-frequency irradiation protection. This segmentation achieves superior performance while maintaining reasonable structural simplicity.
Solution Approach 2:
Each shield serves multiple purposes within its temperature regime. The room-temperature shield provides structural support and magnetic field management, while the low-temperature shield provides thermal isolation and high-frequency field protection. Together they create a multi-functional system that addresses multiple requirements simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses high-frequency magnetic field irradiation to areas outside the observation object, thereby enhancing NMR spectrum resolution and minimizing high-frequency loss by optimizing the placement and size of shields relative to the detection coil.
Implementation Method 1
The detection coil is configured to apply a high-frequency magnetic field to the sample in transmission and detect an NMR signal of the sample in reception
Implementation Method 2
a low-temperature shield between the detection coil and the room-temperature shield, configured to block irradiation of the high-frequency magnetic field from reaching the room-temperature shield
Implementation Method 3
a room-temperature shield between the sample container and the detection coil, configured to block irradiation of the high-frequency magnetic field from reaching a region other than an observation object
Implementation Method 4
Since cooled superconductors have almost zero electrical resistance, superconductors can reduce the above-described noise and improve the detection sensitivity of the NMR signal
Data Source
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AI summary
A sample pipe (46) is provided in a sample temperature control pipe (40). A detection coil (56) is provided in a low-temperature airtight chamber (48) and configured to irradiate a sample with a high-frequency magnetic field. A room-temperature shield (70) is provided on an outer circumferential surface of the sample temperature control pipe (40) or on an inner circumferential surface thereof, and is configured to block irradiation of the high-frequency magnetic field from the detection coil (56) from reaching a region other than an observation object. A low-temperature shield (60) is provided in an airtight chamber (48) and between the detection coil (56) and the room-temperature shield (70) and is configured to block irradiation of the high-frequency magnetic field from the detection coil (56) from reaching the room-temperature shield (70).